First things first: why are we breeding trees?
I have seen many cases where companies start a breeding program because ‘everybody else has got one’. Although that might be the case, there is no point on investing in developing superior genotypes if there is no clear idea of what is a better tree.
Even if the title question seems to be trivial, avoiding it is one of the main reasons why many breeding programs deliver results way below their potential. For most organisations the answer to the question should be ‘we want to breed for long-term profit maximisation’. Therefore, the biological traits that they would want to change must influence profit.
If profit in your organisation depends on a single trait consider yourself lucky. That is the simplest possible situation and your breeding objective will be, for example, ‘to maximise merchantable volume at rotation age’. Nevertheless, for most of us life is not that simple, and profit will depend on several traits. As an example, if your organisation’s final products are wood chips and payment is based on tons of dry wood, profit will probably depend on volume, wood density and pulp yield.
Once you establish which traits have economic importance and are heritable (so there is hope of changing their average through breeding), the next question is ‘What is the relative economic importance of each trait?’ Another way of presenting this question is ‘how much money is worth increasing volume by one cubic metre per hectare (for example) versus changing wood density by one kilogram per cubic metre (again, for example)?’ This will guide your work as to what should be the emphasis of the breeding program.
You may be thinking that the answer to this question involves a lot of work. The answer is yes and no. A very accurate and precise answer requires an inordinate amount of work. However, a rough answer — which is all that we need — can be obtained with a reasonable amount of work and requires no more than a spreadsheet software to be worked out.
Once we have the list of traits to improve and their respective economic weights we have a formally defined breeding objective. This will be the guide for all your future breeding work and will help you to move your program fast and, more importantly, in the right direction.
Note: This article assumes that you already know a few things, including what species you are working with and what are you planning to do with the trees (pulp them, saw them, etc). If you don’t have these answers you most likely don’t need a breeding program, but actually to define the business you are in first!
Resources
- A much more detailed explanation of this problem can be found in Why are most breeders not using economic breeding objectives? (PDF 150KB).
- This site provides a simple online breeding objective calculator for pulp production.
- Yes, Plus Tree actually develops breeding objectives.